JP2004128798A - Radio terminal, method for controlling delay between ends thereof, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform appropriate power-saving operation within a range where the delay time between ends can be suppressed below a prescribed reference value. <P>SOLUTION: In a radio terminal 10<SB>A</SB>, the delay time between ends that is delay time required by the transmission and reception of end-to-end is measured by using a PING packet in an IP network, the time stamp function of RTCP in VoIP communication, or the like by an end-to-end delay acquisition section. In an activation period change judgment module provided in the radio terminal 10<SB>A</SB>, the activation period of a radio communication module is changed. In the radio communication module, radio communication is made so that the delay time between ends measured by the end-to-end delay acquisition section becomes the reference value being prescribed in advance or less. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wireless terminal that performs a power saving operation by intermittently activating a wireless communication module for performing wireless communication with a wireless base station, and in particular, a delay required for end-to-end (between terminal) transmission and reception. The present invention relates to an end-to-end delay control method for suppressing an end-to-end delay time, which is a time, to a specified reference value or less.
[0002]
[Prior art]
In a wireless packet communication system defined in IEEE 802.11 or the like, a power saving mode (power save mode) in which a receiver is periodically activated (wake-up) to transmit and receive packets is defined.
[0003]
An outline of the power saving mode operation in IEEE 802.11 will be briefly described with reference to FIG.
[0004]
The wireless base station broadcasts a beacon packet to all wireless terminals at a fixed period, and all wireless terminals associated with the wireless base station can receive the beacon packet.
[0005]
The wireless terminal that wants to reduce power consumption shifts to the power saving mode, starts and transmits and receives radio waves only during the time when the wireless base station transmits a beacon, and stops energizing the wireless communication module at other times, Shift to sleep state where radio wave transmission / reception is not performed. Since the wireless terminal in the sleep state cannot transmit and receive packets, the wireless base station grasps which wireless terminal is performing the power saving operation, and stores the packet addressed to the wireless terminal in the power saving mode. Then, the wireless base station notifies each wireless terminal of which wireless terminal is currently storing the packet by using a beacon packet that is periodically transmitted.
[0006]
The wireless terminal that has received the packet arrival notification by the beacon packet from the wireless base station immediately replies to the arrival notification and notifies the wireless base station that the packet can be received. The wireless base station receiving the response from the wireless terminal immediately transfers the stored packet.
[0007]
By doing so, the wireless terminal performing the power saving operation can receive the data packet without dropping it even if the wireless terminal is activated only while the beacon packet is being transmitted. In the following description, a time interval in which the wireless communication module is repeatedly turned on and off is referred to as a “start cycle”.
[0008]
In addition, the wireless terminal performing the power saving operation can skip the activation (energization) in an arbitrary beacon cycle. In FIG. 9, the wireless terminal A is activated every period, but the wireless terminal B is activated every other period. By doing so, it is possible to further reduce the power consumption as compared with the case of starting every cycle.
[0009]
On the other hand, a disadvantage of the power saving mode operation is that a packet transfer delay occurs. That is, since the packet is stored in the wireless base station from when the packet arrives at the wireless base station until the activation cycle of the destination wireless terminal of the packet arrives, the packet is delayed by a maximum of the activation cycle time of the destination wireless terminal. Will occur. That is, as the wireless terminal attempts to obtain a greater power saving effect, the delay time and jitter (delay in the delay time) in the wireless section increase.
[0010]
An operator who provides a voice service using VoIP (Voice over Internet Protocol) or the like on an IP network needs to satisfy a voice quality standard formulated by the Ministry of Internal Affairs and Communications. Currently, three grades of classes A to C are defined as VoIP quality evaluation criteria, and it is necessary that the total transmission quality rate (R value), end-to-end delay, and call loss rate satisfy the reference values in FIG. That is, the end-to-end delay time is defined as less than 100 ms for class A, less than 150 ms for class B, and less than 400 ms for class C. Here, the end-to-end delay time means a delay time required for end-to-end (terminal-to-terminal) transmission and reception.
[0011]
However, since the wireless terminal operating in the power saving mode as described above is periodically activated to reduce power consumption, when a VoIP call is attempted in the power saving mode, The addition of the delay in the section may make it impossible to satisfy the specified quality.
[0012]
On the other hand, if the power saving operation is not performed, the delay time in the wireless section can be minimized, but a practical call time cannot be obtained when the mobile terminal is driven by a battery like a mobile terminal.
[0013]
As a conventional end-to-end delay control method for suppressing the end-to-end delay to a reference value or less, a data transfer system measures a delay time in a transmission line, and when the value does not satisfy a reference value, a bit rate or a communication bandwidth is not measured. (For example, see Patent Documents 1 and 2). However, none of these prior arts has a wireless section in a transmission path, and even if such a conventional technique is used, the wireless section delay due to the power saving operation in the wireless terminal described above is suppressed. I can't.
[0014]
[Patent Document 1]
JP-A-2002-204278
[Patent Document 2]
JP 2002-135330 A
[0015]
[Problems to be solved by the invention]
In the above-described conventional wireless terminal and its end-to-end delay control method, when the wireless terminal performs a power saving operation, the end-to-end delay time may not be able to be suppressed to a specified reference value or less. was there.
[0016]
An object of the present invention is to provide a wireless terminal and an end-to-end delay control method that can perform an optimal power-saving operation within a range in which an end-to-end delay time can be suppressed to a specified reference value or less.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, the wireless terminal of the present invention is a wireless terminal that performs a power saving operation by intermittently activating a wireless communication module for performing wireless communication with a wireless base station,
End-to-end delay acquisition means for measuring an end-to-end delay time, which is a delay time required for end-to-end transmission and reception,
A start cycle change determining unit that changes a start cycle of the wireless communication module so that the end-to-end delay time measured by the end-to-end delay obtaining unit is equal to or less than a predetermined reference value. And
[0018]
According to the present invention, the start-up cycle of the wireless communication module is changed so that the end-to-end delay time measured by the end-to-end delay acquisition unit falls below the specified reference value. Optimal power saving operation can be performed within a range that can be suppressed to a specified reference value or less.
[0019]
In order to achieve the above object, a wireless terminal of the present invention performs a power saving operation by intermittently activating a wireless communication module for performing wireless communication with a wireless base station. At
End-to-end delay acquisition means for measuring an end-to-end delay time, which is a delay time required for end-to-end transmission and reception,
A startup cycle notification packet transmitting / receiving means for transmitting a startup cycle notification packet for notifying the communication partner terminal of its own startup cycle and receiving a startup cycle notification packet from the communication partner terminal,
When the end-to-end delay time measured by the end-to-end delay acquisition means is equal to or greater than a predetermined reference value, the start cycle notification packet is transmitted to the communication partner terminal by instructing the start cycle notification packet transmitting / receiving means. Then, the start cycle notified by the start cycle notification packet from the communication partner terminal is compared with the self-start cycle, and if the self-start cycle is greater than or equal to the start cycle of the communication partner terminal, the self-start is performed. And a start cycle change determining unit for making a change to shorten the cycle.
[0020]
According to the present invention, the end-to-end delay acquiring unit monitors whether the end-to-end delay time satisfies a specified standard at regular time intervals using an RTCP packet even during communication, and If the criterion is not satisfied, the activation cycle change determination means changes the activation cycle dynamically (real time). Therefore, even when connecting to a communication partner with a different network environment or when the network delay time changes during communication, it is possible to keep the end-to-end delay time below a certain value while maintaining the optimal power saving state. As a result, the quality of the voice call can be guaranteed without significantly impairing the battery operation time. In addition, an operation in which a terminal having a longer activation cycle makes a change to shorten its own activation cycle does not prevent only one of the terminals from shortening the activation cycle. Unfairness is unlikely to occur.
[0021]
In another wireless terminal according to the present invention, the end-to-end delay obtaining means may measure the end-to-end delay time based on a time required for a packet to reciprocate with a communication partner terminal. Further, a PING packet or an RTCP packet may be used as the packet.
[0022]
Further, in order to achieve the above object, the wireless terminal of the present invention is a wireless terminal performing a power saving operation by intermittently starting a wireless communication module for performing wireless communication with a wireless base station. ,
A network delay time from the wireless base station to a fixed terminal connectable without a wireless section, a network delay time database stored for each fixed terminal,
Before starting communication with the fixed terminal, a network delay time from a wireless base station to a fixed terminal of a communication partner is acquired from the network delay time database, and the network delay time and the wireless communication to the wireless base station are obtained. By adding the section delay time, the end-to-end delay time, which is the time required for end-to-end transmission / reception, is calculated, and the end-to-end delay time of the wireless communication module is suppressed to a specified reference value or less. And a starting cycle change determining unit that changes the starting cycle.
[0023]
According to the present invention, the wireless terminal is provided with the network delay time database in which the network delay time of the fixed terminal that is the communication partner is stored. Can calculate the end-to-end delay time when connected to the fixed terminal of the communication partner. The activation cycle change determination means performs the power saving operation of the wireless communication module at an activation cycle such that the end-to-end delay time is suppressed to a specified reference value or less. Therefore, each time the destination of the communication connection changes, an optimal startup cycle within a range in which the end-to-end delay time can be suppressed to a specified reference value or less according to the network delay time of the connected fixed terminal is selected. It is possible to do.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
[0025]
(1st Embodiment)
FIG. 1 is a system diagram showing a configuration of a wireless communication system including a wireless terminal according to the first embodiment of the present invention.
[0026]
The wireless communication system according to the present embodiment includes a wireless terminal 10 _A , 10 _B And the radio base station 40 ₁ , 40 ₂ And the radio base station 40 ₁ , 40 ₂ Are connected by a WAN (Wide Area Network: wide area network) 50.
[0027]
Wireless terminal 10 _A Has an end-to-end delay obtaining unit 11, a startup cycle change determination module 12, and a wireless communication module 13, as shown in FIG. Wireless terminal 10 _B The configuration of the wireless terminal 10 _A Since the configuration is the same as that described above, the description is omitted.
[0028]
The wireless communication module 13 includes a wireless base station 40 ₁ , 40 ₂ A module having a transmission / reception function for performing wireless communication with the module.
[0029]
The end-to-end delay acquisition unit 11 is configured to provide a delay time required for end-to-end transmission / reception (hereinafter referred to as an end-to-end delay time), _A Transmitted from the wireless terminal 10 _B Measure the time to arrive.
[0030]
As a method for the end-to-end delay obtaining unit 11 to measure the round trip time of a packet during communication, there is a method using a PING packet in an IP network, a time stamp function of RTCP (RTP Control Protocol) in VoIP communication, or the like.
[0031]
The PING packet is a type of ICMP (Internet Control Message Protocol), and a device that implements the IP protocol always has a function of transmitting and receiving ICMP. Since the device that has received the PING packet immediately transmits the same packet to the transmission source, it is possible to measure the round trip time of the network using this mechanism.
[0032]
An RTCP (RTP Control Protocol) packet is a control packet exchanged in VoIP communication, and records in the packet a time when the packet sender last received the RTCP packet and a time difference from the reception time to the transmission of the RTCP packet. ing. The RTCP packet receiver records the time at which the RTCP packet was transmitted, so that the network round trip time can be calculated when the RTCP packet is received.
[0033]
Then, the end-to-end delay obtaining unit 11 can measure the end-to-end delay time by halving the round trip time of the network obtained as described above.
[0034]
The activation cycle change determination module 12 controls the activation of the wireless communication module 13, and controls the wireless communication module so that the end-to-end delay time measured by the end-to-end delay obtaining unit 11 becomes equal to or less than a predetermined reference value. 13 is changed. Here, the activation cycle refers to a time interval in which the power supply to the power supply of the wireless communication module 13 is repeatedly turned off.
[0035]
Next, the operation of the wireless terminal according to the present embodiment will be described in detail with reference to the drawings.
[0036]
In the network having the configuration as shown in FIG. _A , 10 _B Is performing voice communication by packet communication. Terminal 10 _A Performs a power saving (power save) operation specified in, for example, IEEE 802.11 in order to suppress power consumption. That is, the wireless communication module is energized intermittently to transmit and receive packets. At this time, the wireless terminal 10 _A (Or the wireless terminal 10 _A , 10 _B In both cases, the end-to-end delay time is measured by the end-to-end delay acquisition unit 11. The activation cycle change determination module 12 determines whether or not the measurement result satisfies a prescribed reference value. If the measurement result does not satisfy the reference value, the wireless communication is performed so as to suppress the end-to-end delay time to a certain value or less. The activation cycle of the module 13 is changed.
[0037]
Wireless terminal 10 of the present embodiment _A , 10 _B According to the method, the startup cycle of the wireless communication module 13 is changed so that the measured end-to-end delay time falls below the specified reference value, so that the end-to-end delay time is suppressed to the specified reference value or less. An optimum power saving operation can be performed within a range in which the power saving operation can be performed.
[0038]
(Second embodiment)
Next, a wireless terminal according to a second embodiment of the present invention will be described. In the first embodiment described above, the present invention is applied to a general wireless communication system. However, the present embodiment shows a case in which the present invention is applied to a wireless communication system performing a VoIP service. Things. FIG. 3 is a system diagram showing a configuration of a wireless communication system including a wireless terminal according to the second embodiment of the present invention.
[0039]
In this wireless communication system, as shown in FIG. 3, an IEEE 802.11 wireless LAN base station 70 ₁ , 70 ₂ Are connected to the Internet 60 at different points. This wireless communication system includes a wireless LAN base station 70. ₁ , 70 ₂ VoIP terminal 20 that can communicate with each other _A , 20 _B Exists, and these wireless VoIP terminals 20 _A , 20 _B Is operating in a power saving mode defined by IEEE 802.11. Wireless VoIP terminal 20 performing power saving mode operation in IEEE 802.11 _A , 20 _B Reduces the power consumption by intermittently activating the wireless communication module as described above.
[0040]
In the present embodiment, the wireless LAN base station 70 ₁ , 70 ₂ The beacon period of each is 100 ms, and the wireless VoIP terminal 20 _A Is 100 ms and the wireless VoIP terminal 20 _B Is 200 ms. Also, the wireless VoIP terminal 20 _A , 20 _B Must satisfy the class C voice quality standard defined by the Ministry of Internal Affairs and Communications in VoIP shown in FIG. Also, the wireless LAN base station 70 ₁ , 70 ₂ The network delay time between them is 150 ms.
[0041]
Next, the wireless VoIP terminal 20 in the present embodiment _A 4 is shown in FIG. 4, the same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. Also, the wireless VoIP terminal 20 _B The configuration of the wireless VoIP terminal 20 _A Since the configuration is the same as that described above, the description thereof is omitted.
[0042]
Wireless VoIP terminal 20 in the present embodiment _A As shown in FIG. 4, the timer module 21, the end-to-end delay measuring unit 22, the RTP transmitting / receiving module 23, the RTCP transmitting / receiving module 24, the wireless communication module 25, the activation cycle notification packet transmitting / receiving unit 26, A start cycle change determination unit 27 is provided.
[0043]
The timer module 21 counts a set time. The wireless communication module 25 includes a wireless base station 70 ₁ This is a module having a function for performing wireless communication with the module. The RTP transmission / reception module 23 transmits and receives RTP (Real-time Transport Protocol) packets, and the RTCP transmission / reception module 24 transmits and receives RTCP packets.
[0044]
The end-to-end delay measuring unit 22 measures the end-to-end delay time at regular intervals counted by the timer module 21 using the RTCP packets transmitted and received by the RTCP transmitting and receiving module 24.
[0045]
The activation cycle notification packet transmitting / receiving unit 26 transmits an activation cycle notification packet for notifying its own activation cycle to the communication partner terminal in accordance with an instruction from the activation cycle change determination unit 27, and transmits the activation cycle notification packet from the communication partner terminal. The boot cycle notification packet is being received.
[0046]
When the end-to-end delay time measured by the end-to-end delay measurement unit 22 is equal to or greater than a preset reference value, the activation cycle change determination unit 27 instructs the activation cycle notification packet transmitting / receiving unit 26 to execute its own current cycle. A start cycle notification packet is sent to notify the communication partner of the start cycle, and the start cycle notified by the start cycle notification packet from the communication partner is compared with its own start cycle. If the activation period is longer than or equal to the activation period of the partner terminal, a change is made to shorten the activation period of the terminal itself.
[0047]
The timer module 21, the end-to-end delay measurement unit 22, the RTP transmission / reception module 23, and the RTCP transmission / reception module 24 in the present embodiment are the wireless terminal 10 of the first embodiment shown in FIG. _A Corresponds to the end-to-end delay obtaining unit 11 in FIG.
[0048]
Next, the operation of the wireless terminal according to the present embodiment will be described in detail with reference to the drawings.
[0049]
Here, the wireless VoIP terminal 20 _A Is the wireless VoIP terminal 20 _B The case where transmission and reception of voice data is started by VoIP will be described. Under the above conditions, the wireless VoIP terminal 20 _A , The wireless section delay is 100 ms at the maximum, and the wireless VoIP terminal 20 _B In this case, the wireless section delay is 200 ms at the maximum, and the end-to-end delay time is 450 ms at the maximum, and the class C quality condition cannot be cleared. Hereinafter, the wireless VoIP terminal 20 _A Will be described with reference to the block diagram of FIG. 4 and the flowchart of FIG.
[0050]
First, the wireless VoIP terminal 20 _A And wireless VoIP terminal 20 _B When communication starts with the wireless VoIP terminal 20 (step 101). _A Then, the timer is set in the timer module 21 (step 102). Then, by stopping the processing until the timer module 21 times out, a certain period of time is counted (step 103).
[0051]
Wireless VoIP terminal 20 _A The end-to-end delay measurement unit 22 of the wireless VoIP terminal 20 _B Calculate the end-to-end delay time from the time stamp information of the RTCP packet received from (step 104). The startup cycle change determination unit 27 determines whether the end-to-end delay time calculated by the end-to-end delay measurement unit 22 is equal to or longer than 400 ms, which is a class C reference (step 105). Here, since the end-to-end delay time is 450 ms at the maximum, it is 400 ms or more, which is the reference of the class C, and the wireless VoIP terminal 20 _A The activation cycle change determination unit 27 of the wireless VoIP terminal 20 _A , 20 _B Recognize that it is necessary to reduce the end-to-end delay time. Then, the wireless VoIP terminal 20 _A The activation period change determination unit 27 of the wireless VoIP terminal 20 uses the activation period notification packet transmitting / receiving unit 26. _B Then, an activation cycle notification packet is transmitted to the server (step 106). With this activation cycle notification packet, the wireless VoIP terminal 20 _A 100 ms which is the current activation interval of the wireless VoIP terminal 20 _B Will be notified. As a response to this notification, the wireless VoIP terminal 20 _B Sets the start-up interval of its own 200 ms to the wireless VoIP terminal 20. _A Notify
[0052]
Next, the wireless VoIP terminal 20 _A , 20 _B The activation cycle change determination unit 27 compares the activation cycles with each other (step 107). If the activation cycle is longer or equal to the activation cycle of the communication partner, the activation interval change determination unit 27 sets the activation interval to a smaller value. (Step 108).
[0053]
Here, the wireless VoIP terminal 20 _A Is 100 ms, the wireless VoIP terminal 20 _B Of the wireless VoIP terminal 20 having a longer startup cycle because the startup cycle of the _B Changes the startup cycle to a shorter value. That is, the wireless VoIP terminal 20 _B The activation cycle change determination unit 27 of the wireless VoIP terminal 20 _B Of the wireless communication module 25 is shortened from two beacons to one. By performing such processing, the wireless VoIP terminal 20 _B Is 100 ms at the maximum, the end-to-end delay is 350 ms at the maximum, and the class C delay requirement is satisfied.
[0054]
As another example, if, for example, the network delay time is 250 ms, the wireless VoIP terminal 20 _B However, even if the start interval is changed from 200 ms to 100 ms, the end-to-end delay time is still 450 ms, and cannot satisfy the class C requirement. The wireless VoIP terminal 20 in this case _A , 20 _B Is as follows.
[0055]
Wireless VoIP terminal 20 _A , 20 _B Exchanges the first activation cycle notification packet, the wireless VoIP terminal 20 _B Changes the start cycle to 100 ms. After that, the wireless VoIP terminal 20 _A Measures the end-to-end delay time again by the RTCP packet after a predetermined time, and recognizes that the end-to-end delay time exceeds 400 ms.
[0056]
Then, the wireless VoIP terminal 20 _A , 20 _B Exchange the activation cycle notification packets with each other as in the first case, and notify the activation interval. In this case, the wireless VoIP terminal 20 _A , 20 _B Since both have the same value at 100 ms, both terminals try to reduce the radio section delay. Since the activation interval at this time is one beacon for both, and is the shortest interval, both of them shift from the power saving mode to the normal mode to reduce the wireless section delay.
[0057]
According to the end-to-end delay control method according to the present embodiment, the end-to-end delay time is periodically monitored during communication to determine whether or not the specified criterion is satisfied, and the specified criterion is not satisfied In this case, the start cycle is changed dynamically (real time). Therefore, even when connecting to a communication partner with a different network environment or when the network delay time changes during communication, it is possible to keep the end-to-end delay time below a certain value while maintaining the optimal power saving state. As a result, the quality of the voice call can be guaranteed without significantly impairing the battery operation time.
[0058]
In the present embodiment, the case where the end-to-end delay time is measured using the RTCP packet has been described. However, the case where the end-to-end delay time is measured using a PING packet or the like other than the RTCP packet, or another method. Therefore, the end-to-end delay control method according to the present embodiment can be similarly applied to the case where the end-to-end delay time is measured.
[0059]
(Third embodiment)
Next, a wireless terminal according to a third embodiment of the present invention will be described. In the second embodiment described above, the communication partner terminal is also a wireless terminal. However, in the present embodiment, the communication partner is a fixed terminal that can be connected from the wireless base station without passing through a wireless section. There are some differences.
[0060]
When the communication partner is a fixed terminal, the change in end-to-end delay time after communication starts is small, but the network delay time differs for each fixed terminal to be connected. For this reason, in the wireless terminal of the present embodiment, the start cycle of the wireless communication module is changed at the start of communication so that the end-to-end delay time falls below the specified reference value, and the continuous end-to-end delay time during communication is reduced. Monitoring is not performed. FIG. 6 is a system diagram showing a configuration of a wireless communication system including a wireless terminal according to the third embodiment of the present invention. 6, the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.
[0061]
In this wireless communication system, as shown in FIG. 6, an IEEE 802.11 wireless LAN base station 70 connected to the Internet 60 ₁ Exists and its wireless LAN base station 70 ₁ Wireless VoIP terminal 20 that communicates using _C Exists.
[0062]
The VoIP terminal 30 connected to the Internet 60 via a link with a small delay as a fixed terminal that can be connected from the wireless LAN base station 701 without going through a wireless section. _D And the VoIP terminal 30 connected to the Internet 60 by a link with a large delay _E Exists.
[0063]
Wireless LAN base station 70 ₁ Of the wireless VoIP terminal 20 is 100 ms. _C Is performing a power saving operation, and the startup cycle is 200 ms. Also, the wireless LAN base station 70 ₁ To VoIP terminal 30 _D Network delay time to the wireless LAN base station 70 ₁ To VoIP terminal 30 _E It is assumed that the network delay time to is 250 ms.
[0064]
Wireless VoIP terminal 20 _C Is the VoIP terminal 30 _D And VoIP terminal 30 _E The network delay of the route when communicating with the network is measured in advance, and is stored in a network delay time database provided inside.
[0065]
Also, the wireless VoIP terminal 20 _C Is required to satisfy the class C rule shown in FIG. 10 as the VoIP communication quality. That is, the wireless VoIP terminal 20 _C It is assumed that the end-to-end delay during a VoIP call needs to be suppressed to less than 400 ms.
[0066]
Next, the wireless VoIP terminal 20 in the present embodiment _C 7 is shown in FIG. 7, the same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.
[0067]
Wireless VoIP terminal 20 in the present embodiment _C As shown in FIG. 7, the RTP transmission / reception module 23, the RTCP transmission / reception module 24, the wireless communication module 25, the network delay time database 31, and the activation cycle change determination unit 37 are provided.
[0068]
The network delay time database 31 includes a wireless LAN base station 70. ₁ From each VoIP terminal 30 _D , 30 _E Is stored for each VoIP terminal. Specifically, the network delay time database 31 stores the wireless LAN base station 70 for each address (identifier) or network address or domain name of the VoIP terminal of the communication partner. ₁ The network delay time from is stored.
[0069]
The activation cycle change determination unit 37 acquires the network delay time of the VoIP terminal of the communication partner from the network delay time database 31 before starting communication, and compares the network delay time with the wireless LAN base station 70. ₁ The end-to-end delay time is calculated by adding the end-to-end wireless section delay time to the wireless communication module 25, and the power-saving operation of the wireless communication module 25 is performed at a startup cycle such that the end-to-end delay time is suppressed to a specified reference value or less. I do.
[0070]
Hereinafter, the wireless VoIP terminal 20 in the present embodiment _C Will be described with reference to the flowcharts of FIGS. 6, 7, and 8. FIG.
[0071]
First, the wireless VoIP terminal 20 _C Is the VoIP terminal 20 _D In the following, an operation when a voice call is to be started using VoIP will be described.
[0072]
Wireless VoIP terminal 20 _C First, the VoIP terminal 30 is retrieved from the network delay time database (DB) 31 held therein. _D 100 ms, which is the expected value of the network delay time when communicating with the server, is acquired (step 201).
[0073]
Next, the wireless VoIP terminal 20 _C The activation cycle change determination unit 37 calculates the end-to-end delay time with the VoIP terminal 30D (step 202). The end-to-end delay time is determined by the wireless VoIP terminal 20. _C Is the sum of the wireless section delay time and the network delay time. Wireless VoIP terminal 20 _C The wireless section delay time is 200 ms at the maximum, which is the same as the activation period, and the end-to-end delay time is 100 ms at the maximum and 300 ms at the maximum.
[0074]
Next, the activation cycle change determination unit 37 compares the obtained maximum value of the end-to-end delay time of 300 ms with the specified value of the class C delay time of 400 ms (step 203).
[0075]
Here, the maximum value of the obtained end delay time is 300 ms, which satisfies the class C standard that the delay time is less than 400 ms. _C Without changing the activation cycle of the wireless VoIP terminal 20 _C Is the VoIP terminal 30 while maintaining the startup cycle. _D And VoIP communication are started (step 205).
[0076]
Next, the wireless VoIP terminal 20 _C Is the VoIP terminal 30 _E The operation in the case where a voice call is made by using VoIP is described.
[0077]
Wireless VoIP terminal 20 _C First, the VoIP terminal 30 is retrieved from the network delay time database (DB) 31 held therein. _E 250 ms, which is the expected value of the network delay time when communicating with the server, is acquired (step 201).
[0078]
Next, the wireless VoIP terminal 20 _C The activation cycle change determination unit 37 of the VoIP terminal 30 _E Is calculated (step 202). Wireless VoIP terminal 20 _C The wireless section delay time is 200 ms at the maximum, which is the same as the activation cycle, and the VoIP terminal 30 _E The end-to-end delay time is a maximum of 450 ms by adding the network delay time of 250 ms.
[0079]
Next, the activation cycle change determination unit 37 compares the obtained maximum value of the end-to-end delay time 450 ms with the specified value of the class C delay time 400 ms (step 203).
[0080]
Here, since the end-to-end delay time 450 ms does not satisfy the value less than the prescribed value of 400 ms of the class C, the activation cycle change determination unit 37 suppresses the end-to-end delay time to within 400 ms which is the reference of the class C. The activation cycle is reduced to one beacon, that is, 100 ms (step 204). As a result, the wireless section delay time becomes a maximum of 100 ms, and the end-to-end delay becomes a maximum of 350 ms, so that VoIP communication satisfying the class C standard becomes possible.
[0081]
Wireless VoIP terminal 20 of the present embodiment _C According to the VoIP terminal 30 as a communication partner, _D , 30 _E The network delay time database 31 stores the network delay time of the VoIP terminal of the communication partner and the wireless LAN base station 70 before starting the communication. ₁ The end-to-end delay time is calculated by adding the end-to-end delay time to the wireless communication module 25, and the power-saving of the wireless communication module 25 is performed at a start cycle such that the end-to-end delay time is suppressed to a specified reference value or less. Perform the operation. Therefore, each time the destination of the communication connection changes, an optimum startup cycle within a range in which the end-to-end delay time can be suppressed to a specified reference value or less according to the network delay time of the connected VoIP terminal is selected. It is possible to do.
[0082]
That is, the wireless VoIP terminal 20 of the present embodiment _C According to this, even when a VoIP call is made with a VoIP terminal having various network environments, the restriction of the delay time can be satisfied at the start of the call, and the call quality can be guaranteed without significantly impairing the battery drive time. .
[0083]
In the present embodiment, all VoIP terminals 30 that may be connected as communication partners _D , 30 _E Has been described as being stored in the network delay time database 31, but the present invention is not limited to such a case, and the wireless terminal stores the network delay time in the network delay time database 31. When a new VoIP terminal that has not been connected is connected, the network delay time of the new VoIP terminal may be measured and added to the network delay time database 31 automatically.
[0084]
In the present embodiment, the network delay time database 31 stores the _C Although the description is made using the case provided in the inside, the present invention is not limited to such a case. The network delay time is a database corresponding to the network delay time database 31. ₁ Any configuration provided in the inside may be used. With such a configuration, the wireless VoIP terminal 20 _C It is possible to reduce the amount of data that must be stored in the storage. In the case of such a configuration, the wireless VoIP terminal 20 _C Starts wireless LAN base station 70 when starting communication with delay time restrictions such as VoIP communication. ₁ The network delay time of the VoIP terminal as the communication partner is acquired from the above database. Then, the wireless VoIP terminal 20 _C Can change the startup interval in the power saving mode based on the network delay time, so that the end-to-end delay time can be suppressed to a specified reference value or less.
[0085]
Furthermore, a configuration may be adopted in which a database server that stores the network delay time from the wireless base station to each VoIP terminal is provided on the network to which the wireless terminal belongs.
[0086]
Although not shown in the drawings, the wireless terminals according to the first to third embodiments of the present invention include a recording medium storing a program for executing the above-described method for measuring an end-to-end delay time. ing. This recording medium may be a magnetic disk, a semiconductor memory or another recording medium. This program is read from the recording medium by the wireless terminal and controls the operation of the wireless terminal. Specifically, the above processing is realized by the CPU in the wireless terminal instructing the hardware resources of the wireless terminal to perform a specific process under the control of this program.
[0087]
【The invention's effect】
As described above, according to the present invention, in the wireless terminal, the end-to-end delay acquisition unit measures the end-to-end delay time, so that the measured end-to-end delay time falls below a specified reference value. Since the activation cycle of the wireless communication module is changed by the activation cycle change determination unit, an optimal power saving operation can be performed within a range in which the end-to-end delay time can be suppressed to a specified reference value or less. Can be obtained.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a configuration of a wireless communication system including a wireless terminal according to a first embodiment of the present invention.
FIG. 2 shows a wireless terminal 10 according to the first embodiment of the present invention. _A FIG. 3 is a block diagram showing the configuration of FIG.
FIG. 3 is a system diagram showing a configuration of a wireless communication system including a wireless terminal according to a second embodiment of the present invention.
FIG. 4 shows a wireless VoIP terminal 20 according to a second embodiment of the present invention. _A FIG. 3 is a block diagram showing the configuration of FIG.
FIG. 5 shows a wireless VoIP terminal 20 according to a second embodiment of the present invention. _A 5 is a flowchart showing the operation of the first embodiment.
FIG. 6 is a system diagram showing a configuration of a wireless communication system including a wireless terminal according to a third embodiment of the present invention.
FIG. 7 shows a wireless VoIP terminal 20 according to a third embodiment of the present invention. _C FIG. 3 is a block diagram showing the configuration of FIG.
FIG. 8 shows a wireless VoIP terminal 20 according to a third embodiment of the present invention. _C 5 is a flowchart showing the operation of the first embodiment.
FIG. 9 is a diagram illustrating an operation in a power saving mode.
FIG. 10 is a diagram showing quality classes of IP telephones.
[Explanation of symbols]
10 _A , 10 _B Wireless terminal
11 End-to-end delay acquisition unit
12 Start cycle change judgment module
13 Wireless communication module
20 _A ~ 20 _B Wireless VoIP terminal
21 Timer module
22 End-to-end delay measurement unit
23 RTP transmission / reception module
24 RTCP transceiver module
25 wireless communication module
26 Startup cycle notification packet transmitting / receiving unit
27 Start cycle change judgment unit
30 _D , 30 _E VoIP terminal
31 Network delay time database
37 Start cycle change judgment unit
40 ₁ , 40 ₂ Wireless base station
50 WAN
60 Internet
70 ₁ , 70 ₂ Wireless LAN base station
101-108 steps
201-205 steps

Claims (18)

In a wireless terminal that performs a power saving operation by intermittently activating a wireless communication module for performing wireless communication with a wireless base station,
End-to-end delay acquisition means for measuring an end-to-end delay time, which is a delay time required for end-to-end transmission and reception,
Starting cycle change determining means for changing the starting cycle of the wireless communication module so that the end-to-end delay time measured by the end-to-end delay obtaining means is equal to or less than a predetermined reference value. Characteristic wireless terminal. In a wireless terminal performing a power saving operation by intermittently starting a wireless communication module for performing wireless communication with a wireless base station,
End-to-end delay acquisition means for measuring an end-to-end delay time, which is a delay time required for end-to-end transmission and reception,
A startup cycle notification packet transmitting / receiving means for transmitting a startup cycle notification packet for notifying the communication partner terminal of its own startup cycle and receiving a startup cycle notification packet from the communication partner terminal,
When the end-to-end delay time measured by the end-to-end delay acquisition means is equal to or greater than a predetermined reference value, the start cycle notification packet is transmitted to the communication partner terminal by instructing the start cycle notification packet transmitting / receiving means. Then, the start cycle notified by the start cycle notification packet from the communication partner terminal is compared with the self-start cycle, and if the self-start cycle is greater than or equal to the start cycle of the communication partner terminal, the self-start is performed. A wireless terminal comprising: a start cycle change determining unit that performs a change for shortening a cycle. The wireless terminal according to claim 1, wherein the end-to-end delay acquiring unit measures the end-to-end delay time based on a time required for a packet to reciprocate with a communication partner terminal. The wireless terminal according to claim 3, wherein the packet is a PING packet. The wireless terminal according to claim 3, wherein the packet is an RTCP packet. In a wireless terminal performing a power saving operation by intermittently starting a wireless communication module for performing wireless communication with a wireless base station,
A network delay time from the wireless base station to a fixed terminal connectable without a wireless section, a network delay time database stored for each fixed terminal,
Before starting communication with the fixed terminal, a network delay time from a wireless base station to a fixed terminal of a communication partner is acquired from the network delay time database, and the network delay time and the wireless communication to the wireless base station are obtained. By adding the section delay time, the end-to-end delay time, which is the time required for end-to-end transmission / reception, is calculated, and the end-to-end delay time of the wireless communication module is suppressed to a specified reference value or less. A wireless terminal comprising: a startup cycle change determination unit that changes a startup cycle. Defines end-to-end delay time, which is the delay time required for end-to-end transmission and reception in wireless terminals that perform power-saving operations by intermittently activating a wireless communication module for wireless communication with a wireless base station An end-to-end delay control method for keeping the reference value below a reference value,
Measuring the end-to-end delay time;
Changing the activation cycle of the wireless communication module so that the measured end-to-end delay time is equal to or less than a predetermined reference value. An end-to-end delay time, which is a delay time required for end-to-end transmission and reception in a wireless terminal performing a power saving operation by intermittently activating a wireless communication module for performing wireless communication with a wireless base station. Is a method of controlling end-to-end delay to keep the
Measuring the end-to-end delay time;
When the measured end-to-end delay time is equal to or greater than a preset reference value, transmitting a startup cycle notification packet to the communication partner terminal to notify its own startup cycle to the communication partner terminal,
Comparing the startup cycle notified by the startup cycle notification packet from the communication partner terminal with its own startup cycle,
A step of making a change to shorten the activation cycle of the terminal when the activation cycle of the communication apparatus is longer than or equal to the activation cycle of the communication partner terminal. 9. The end-to-end delay control method according to claim 7, wherein in the step of measuring the end-to-end delay time, the end-to-end delay time is measured based on a time required for a packet to reciprocate with a communication partner terminal. 10. The method according to claim 9, wherein the packet is a PING packet. The method according to claim 9, wherein the packet is an RTCP packet. An end-to-end delay time, which is a delay time required for end-to-end transmission and reception in a wireless terminal performing a power saving operation by intermittently activating a wireless communication module for performing wireless communication with a wireless base station. Is a method of controlling end-to-end delay to keep the
Acquiring a network delay time from a wireless base station to a fixed terminal of a communication partner from a network delay time database before starting communication with the fixed terminal,
Calculating the end-to-end delay time, which is the time required for end-to-end transmission and reception by adding the network delay time and the wireless section delay time to the wireless base station;
Changing the activation cycle of the wireless communication module so that the end-to-end delay time is reduced to a specified reference value or less. Defines end-to-end delay time, which is the delay time required for end-to-end transmission and reception in wireless terminals that perform power-saving operations by intermittently activating a wireless communication module for wireless communication with a wireless base station A program for causing a computer to execute an end-to-end delay control method for suppressing the reference value or less,
A process of measuring the end-to-end delay time;
Changing a startup cycle of the wireless communication module so that the measured end-to-end delay time is equal to or less than a predetermined reference value. An end-to-end delay time, which is a delay time required for end-to-end transmission and reception in a wireless terminal performing a power saving operation by intermittently activating a wireless communication module for performing wireless communication with a wireless base station. Is a program for causing a computer to execute an end-to-end delay control method for suppressing a specified reference value or less,
A process of measuring the end-to-end delay time;
When the measured end-to-end delay time is equal to or greater than a preset reference value, a process of transmitting to the communication partner terminal a startup cycle notification packet for notifying its own startup cycle to the communication partner terminal,
A process of comparing the activation period notified by the activation period notification packet from the communication partner terminal with its own activation period,
A program for causing a computer to execute a process of changing the start cycle of the terminal when the start cycle of the terminal is longer than or equal to the start cycle of the communication partner terminal. The program according to claim 14, wherein in the processing of measuring the end-to-end delay time, the end-to-end delay time is measured based on a round-trip time of a packet with a communication partner terminal. The program according to claim 15, wherein the packet is a PING packet. The program according to claim 15, wherein the packet is an RTCP packet. An end-to-end delay time, which is a delay time required for end-to-end transmission and reception in a wireless terminal performing a power saving operation by intermittently activating a wireless communication module for performing wireless communication with a wireless base station. Is a program for causing a computer to execute an end-to-end delay control method for suppressing a specified reference value or less,
Before starting communication with the fixed terminal, a process of acquiring the network delay time from the wireless base station to the fixed terminal of the communication partner from the network delay time database,
A process of calculating an end-to-end delay time, which is a time required for end-to-end transmission and reception by adding the network delay time and the wireless section delay time to the wireless base station;
Changing a startup cycle of the wireless communication module so that the end-to-end delay time is reduced to a specified reference value or less.

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